Patent GB-512417-A (GB)
Title: Improvements in electrical systems of remote control
IPC: H02J13/00
Filed: 1938-01-01
Abstract: 512,417. Electric control and signalling systems. GENERAL ELECTRIC CO., Ltd., and SMART, N. C. Jan. 1, 1938, No. 1. [Class 40 (i)] In a system of remote control and supervision for a plurality of substations connected in tandem to two pairs of line wires and employing synchronously operated selector switches at the central station and substations, the signalling current which flows in one of the pairs of line wires when a particular selection is made is in such a direction as to indicate the condition of the selected apparatus, e.g., a circuit breaker, and of a' magnitude which is indicative of the value of the current or voltage of the circuit associated with the selected apparatus. Impulses for effecting the selections are transmitted over one pair of line wires and the selections are checked by impulses reverted over the second pair of wires. Normally both pairs of line wires carry supervisory currents for testing for line faults. Provision is made for signalling the automatic operation of an apparatus unit and for indicating an automatic reclosure after tripping. Indication is also given and operation of the stopping switches is stopped in the event of faulty operation of the indicating auxiliary contacts associated with an apparatus unit. Figs. 1, 2 and 3 show the circuits in the control station and Figs. 4 and 5 those at a substation. Selection of apparatus unit. An apparatus unit, e:g., a circuit breaker 90, Fig. 5, is selected by operation of an associated key, e.g., 18, Fig. 1, which marks bank SI of switch S and pulls up a relay k which operates the start relay ST. Relay ST connects battery to line wires 50, 51 and pulls up pulsing relays Y, Z which interact to pulse relay X and step the switches SS. Relay X also controls the reversal of the battery corinections to the line wires and alternate pulses of reverse polarity are transmitted synchronously'with the stepping of switch SS until the contact in bank SSI marked by the relay k and characteristic of the substation to be selected is reached. At the substations polarized line relays h are operated by the positive pulses (i.e., positive potential on line 50) to operate the stepping magnets of the switches ZR which are driven synchronously with the switch SS. At the selected station the switch ZR extends the pulsing circuit to switches governing the selection of the wanted apparatus. Upon cessation of pulsing, a slow relay G in series with the magnet' ZR falls back and a checking train of impulses is reverted to the control station. Checking selection of substation.-Relapse of relay G pulls up relay SO over bank ZR2 if the correct signal has been received and initiates the operation of pulsing relays SW..SZ. Relay SO also applies battery to the lines 52, 53 and pulses in the form of interruptions are transmitted under the control of relays SO, SW.. SZ until a synchronously operated switch ZS reaches a contact marked by the switch ZR. The transmitted pulses operate a polarized relay OR and step a switch SR. If all the pulses are correctly transmitted and received the relay Q is operated over the banks SS2, SR2 of the switches SS, SR. Relay Q transfers the marking and stepping circuits to switches S, R. At the selected substation, relay H effects a similar transfer to the switches XR, XS. Selection of wanted apparatus and checking selection.-When relay Q pulls up, relay CS operates and pulls up relay,X over bank SI and impulsing over the lines 50, 51 is resumed under the control of the switch S.. The transmitted' pulses operate the stepping switch XR until when the switch S reaches the contact marked by the key 18, the switches are stopped and switch XR selects the wanted apparatus, e.g., the circuit breaker 90. When switch XR leaves its second contact, relay SK is released and relay SW falls back to initiate the transmission of a checking train of impulses over the line wires 52, 53 in the manner previously described. This checking operation, however, takes place simultaneously with the selection and relay OR is pulsed to operate the stepping magnet R. Simultaneously at the substation switch XS is stepped and when it overtakes the switch XR, relay SK is operated to terminate impulsing and pull up a relay M which controls the metering equipment associated with' the selected apparatus. If, at the control station, a correct checking signal is received relay OK is operated over the wipers R1, S3 to light a lamp 19 and by means of relay MM remove a short-circuit from a meter 97. Metering.-Relay M drives a motor operated potentiometer 93, 94 into a position corresponding to the electrical value measured by the meter 70 and the potentiometer is connected in series with the line wire 52 and meter 97 at the control station. Operation of selected apparatus. - The selected apparatus is closed or opened by depression of a key 30 or 31, which pulls up a relay OP and thereby energises a buzzer equipment V, V2 which maintains its vibrations and generates A.C. Pulsing relays OX, OY OZ operate a stepping switch OSI and a train of A.C. pulses is sent, the train being broken up by two pauses introduced in accordance with the markings of a switch OSI by the key relays OT, OC. The impulse train operates relay OL which steps a switch TSI to select a relay in the group OU, OE, OG in response to the first pause and the operating coil of the apparatus over the contacts of the selected relay and bank contact of XR1 in response to -the second pause. This arrangement prevents inadvertent operation of the apparatus by interfering signals on the line, the relay OG commoned to unused contacts in bank TSI being operated by interfering pulses to open the operating circuit of the apparatus. Operation of the apparatus causes the alteration in the position of the meter 70 and the new value is indicated on the meter 97. Indicating position of apparatus.-When a circuit breaker, e.g., 90, changes its position contact 91 causes release of relay SO to open the line circuit 52, 53 and operate a relay SG to reverse the battery connections to the line wires and thereby pull up relay CR which operates relay P and lights the appropriate indicating lamp 20 or 21. Restoration to normal.-Release of keys 18, 30 completes self-restoring circuits for the stepping switches at both stations. Signalling automatic operation of substation apparatus and checking positions of all apparatus at the substation.-When an apparatus changes its position relay CB is released and relay TA, Fig. 4, pulls up to connect battery to lines 52, 53. Line relay AL is operated and relay AS pulls up to operate " start " relay ST. Relay ST pulls up polarized line relay OR which operates relay TP which in co-operation with the pulsing relays YZ controls the stepping of the switch SS. The line relays L at the substations are pulsed and the switch ZR is stepped synchronously, each transmitted pulse over lines 50, 51 being released by a pulse reverted over the lines 52, 53 by relay TA provided at the substation at which a change has taken place and released upon receipt of a pulse over lines 50, 51. When switch ZR reaches the contact marked by the apparatus, relay TA is held operated and relay TP at the control station interrupts the impulsing operation. At the substation relay G releases and initiates the transmission of a checking signal which positions switches ZS, SR. A check is now made of the positions of all apparatus at the. affected substation. When the switches SR, SS line up after the receipt of the correct checking signal, relays QX are operated. Relay X controls the stepping of the switches XR, S and after three steps switch S releases relay OK and switch XR releases SK which causes the chain SW.. SZ to impulse the switches XS, R up to a position of alignment with the switches XR, S. This position corresponds to the first apparatus unit and its associated indicator relay P and wiper XS1 or XS2 picks up battery potential in accordance with the position of the unit to operate relay SO or SC and the corresponding relay CR or OR at tthe control station. The relay P thus - operates the appropriate lamp 20, 21. Stepping of the switches S, XR, R, XS is continued under revertive control and the indicator relays are successively operated to positions corresponding to their associated units. Operation under fault conditions.-If the apparatus unit contacts 91 are faulty both re-' lays OY, CY are released upon a change of position and although a checking cycle is initiated it is terminated at the unmarked wipers XS and the control station relays CR, OR remain unoperated. Relay B is released and flicker positive 25 is connected over wiper S2 to flash the lamp 19. Stepping of the switches is restarted by key 15. In order to indicate at the central station that automatic opening and closing of a unit has taken place although no permanent change exists, relay RR is provided which transmits an " open condition " signal to pull up a relay PA in the control station and operate an alarm and flash the operated indicator lamps 20, 21. Line supervisory equipment.-Sensitive relays 70, 71 are connected in the line circuits, each relay having a pair of windings one of which carries current determined by the resistance of the associated line circuit and the other carries a balancing current pre-determined by a resistance 82. The supervisory circuits are supplied from a transformer 81 through rectifier bridges 80. If the line conditions alter the appropriate relay 70, 71 operates to release relay DB or SB and operate an alarm 32 or 33. A rectifier 83 is connected across the lines 50, 51 at each substation to prevent operation of the relay L by the test current. Blowing of a fuse in a substation releases relay FA which bridges both pairs of lines and operates both relays 70, 71 and an alarm 34. Earth leakage on the lines is indicated by an alarm 35 operated by relays EL, 72. Specification 512